Websites like Reddit and Telegram are being blocked in India by internet service providers, throwing into question the enforcement of net neutrality rules, advocacy groups said on Wednesday.

Telegram, which has 200 million global users, has been popular in countries including Russia and Iran.

Iranian President Hassan Rouhani has criticised the ban imposed on popular messaging app Telegram by the conservative-run judiciary, saying the move was "the opposite of democracy".

Human Rights Watch on Wednesday hit back at Iran's ‘unjustifiable’ decision to ban the Telegram messaging app, warning Tehran against stifling access to information.

Iran's judiciary has banned the popular Telegram instant messaging app to protect national security, Iran's state TV reported on Monday.

In an usually strong turnout, at least 8,000 people including top opposition leader Alexei Navalny turned up in the centre of the Russian capital, many holding placards and shooting paper airplanes.

Russia's communications watchdog on Monday began blocking access to the popular messaging app Telegram after a court banned the service for refusing to give security services access to private conversations.

The decision came a week after state communication watchdog, Roskomnadzor, filed a lawsuit to limit access to Telegram following the company's repeated refusal to give Russian state security services access to its users' secret messages.

Iran's telecoms minister said on Wednesday that Telegram would only be unblocked if it removed "terrorist" content after the social media app was shut down during this week's protests.

Indonesia has blocked web-based access to a popular messaging service and threatened a full ban on the app due to its "terrorism" content, the government said.

Iran has "arrested or summoned" around 450 social media users over their online activities, a website linked to the powerful Revolutionary Guards said on Tuesday.